The present invention relates to improvements in dental impression trays and, in particular, to retention means for use in combination with the dental impression trays having enhanced ability to hold the impression material and specially improved facility for separating the compound material from the mouth and the compound material from the tray after the impression has been made.
In order for a dentist to take the impression of a patient's jaw or part of the jaw, he employs a shovel-like tray filled with a plastic or maleable impression compound which solidifies in the mouth of the patient. After solidification, the tray and the solid compound is removed bodily from the mouth and used to cast or mold a replica of the patient's jaw or jaw parts for building replacement bridges and the like.
In order to manipulate the tray and the impression compound before, during, and after impression, the compound and the tray must both be chosen with several seemingly contradictory factors taken into account--namely:
1. The compound must be able to stick to the tray when first applied to it so that it will not slip or fall from the tray when being handled by the dentist.
2. The compound must also be sufficiently adherent to the tissues of the mouth and the gums so that every crack, fold, or crease in the mouth is transferred to the impressioned compound and the compound remains in that condition through the period of time necessary to provide sufficient solidification thereof.
3. On the other hand, the compound cannot stick or adhere too much to the mouth tissues so that it distorts or is damaged upon removal from the mouth.
4. The compound must also be easier to remove from the mouth than from the tray itself so that upon manipulation by the dentist to remove it from the mouth, it does not inadvertantly become separated from the tray itself.
Items 2 or 3 have been more or less successfully dealt with chemically in the creation of the impression compounds. On the other hand, Items 1 and 4 continue to present great problems to dentists or orthodontists because the interaction caused by the dissimilar, physical attributes of the chemical compound and the tray itself have not been successfully dealt with.
Many attempts have been made to provide more agreeable dental tray systems. For example, trays have been made of rigid or flexible metal or plastic. Preferably, such are made with holes to hold the compound. Adhesives, glues, jells, waxes are usually interposed between the surfaces of the tray and the impression compound. While some of these techniques solve one or more of the foregoing difficulties, they simultaneously exacerbate other problems or do not overall, solve all of the problems inherent in the use of different physical characteristics of compound and tray. Reference to U.S. Pat. Nos. 1,955,709; 2,703,452; 4,204,323; 4,530,662; and 4,907,966 may be made for a representative sample of the prior attempts at dealing with this problem.
It is, therefore, an object of the present invention to improve the use of the systems for dental impression compounds and trays.
It is an object to provide a system enhancing the retention of impression compounds on the tray for manipulation before, during, and after the dental impression as well as to provide for the proper separation of the compound from the mouth and the tray.
The foregoing object as well as other objects will be apparent from the following disclosure of the present invention.